Abstract
A method for measuring positive and negative charging characteristics under electron beam irradiation by using a floating target which is connected to the gate of a MOSFET has been described. The relation between the gate voltage and the drain current measured in advance before beam irradiation is used to estimate the induced voltage on the floating target during electron beam irradiation. The voltage resolution is 5 mV and the measurement accuracy of the experiment defined as the reproducibility before and after beam irradiation is within 1%.